A fibre optic tiltmeter [for volcano monitoring]

A simple, rugged and highly sensitive fibre optic tiltmeter has been designed and its prototype model tested. The sensor intensity modulates the light with the change in the level of Hg surface with tilt. Hence, producing a detector output proportional to the tilt angle. The most important attribute of the tiltmeter is its ability to measure tilts of the order of microradians with a high degree of precision, hence making it an important tool for geophysical monitoring. Besides, the dielectric construction and inherent compatibility with fibre optic telemetry make the sensor suitable for monitoring the conditions of hostile and remote sites of volcanoes. The prototype model has been developed using rugged and easy to handle plastic fibres and the results obtained were satisfactory with a sensitivity of approximately 1.0 mV//spl mu/rad.